1. Fields of the Invention
The present invention relates to a chair chassis, especially to a chair chassis by which a force of a seat back can be adjusted. Moreover, lifting and fastening of the chair chassis are adjusted by the same handle. The vibration and friction generated during inclining of the seat back are also reduced. The operation and adjustment of the chair chassis are easier and faster.
2. Descriptions of Related Art
Generally, a chair chassis includes a plurality of components such as an upper support tray, a lower support rod, a shaft, springs, etc. The upper support tray is fixed with and connected to a chair back so that the chair back is adjusted and reclined to different angles around the shaft to make users feel more comfortable. However, the springs used in the chair chassis are torsion spring. During the adjustment process, the force of the torsion spring is unable to be adjusted so that its applicability is limited. Moreover, users need to pull a handle by using a lot of effort while in use. When the chair back is reclined, noises are created due to friction of a brake part. And once the chair back is turned back quickly, users sense the vibration of the chair chassis and feel uncomfortable. Furthermore, a fastening handle and a lift handle of the chair are separated. Thus the adjustment of fastening position and lift range of the chair is inconvenient. There is room for improvement and a need to provide a novel chair chassis.